Suppressing ouput of image when exporting to ePub

I have a small graphic which is to be used as a section break ornament in an ePub file. It's assigned a paragraph style called "Section break ornament" and in the Export Tagging section of this style's dialogue box, it's set to output an hr tag. The following code is what it outputs into the html file:

<hr class="ornament"><img class="_idGenObjectAttribute-3" src="image/4.png" alt="" /></hr>

The graphic in the ID file is really just a placeholder so I don't need it to be exported when the ePub is created (as it is doing in the code above). Instead of using an html img tag in the ePub I plan to set a background image using css. Because of this I need to output the hr tag but not the img tag within the hr tag.

Instead of:

<hr class="ornament"><img class="_idGenObjectAttribute-3" src="image/4.png" alt="" /></hr>

I need the ePub to output this:

<hr class="ornament"></hr>

So just an empty hr tag.

I've checked the object export options dialogue to see if I could switch off the ouput of the image but I don't see an option.

I wondered if someone could tell me if there is a way to do this when exporting to ePub?

Would appreciate any assistance.

Thanks